# Numerical Definitions

GLib offers mathematical constants such as `G_PI`

for the value of pi;
many platforms have these in the C library, but some donâ€™t. The GLib
versions always exist.

The `GFloatIEEE754`

and `GDoubleIEEE754`

unions are used to
access the sign, mantissa and exponent of IEEE floats and doubles. These unions
are defined as appropriate for a given platform. IEEE floats and doubles are
supported (used for storage) by at least Intel, PPC and Sparc. See
IEEE 754-2008
for more information about IEEE number formats.